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My Honda CBR400RRn NC29 Project Bike Part2 - Fork Rebuild

And here they are with the new tubes and seals fitted, ready for fast and furious action, almost...

I also managed to find and ordered a set of collars as the ones on the legs were in bad shape.

I found that the old collars had been glued with some sort of epoxy onto the legs, I am not sure if that was done in the factory but its didn't look very professional so I am assuming somebody who really clumsy and hates bikes did it. Needless to say removing them was not easy and required a fair bit of brute force.

I wont go into all the nitty gritty of how to install seals as its easy enough to find the info online. The hardest part for me was seating the seals as I didn't have a tool for that job. I did the old trick of using the old seals to help seat the new ones but I think if I did this again i would make a tool from a piece of pipe to make the job simpler.

Fitting the new collars also was a right pain in the ass as they are a very tight fit, I ended up having to file a chamfer on the edges and lightly sand the inside of them and only then I was finally able to get them onto the tubes. I used the old collars to help seat the new ones.

Filling them was simple enough once I knew how much oil to add and how to add it.

Comments

Good job on the forks, and write up! I bought a '94 GSXR400 a couple of years ago and while the forks were'nt rusted like yours they were in bad need of attention. The GSXR actually has USD's which is not common on those 250/400 fours form the late eighties onwards. Most of them have too softer springs from the factory so i put some stiffer racetech springs in there at the same time I had them apart. Not real cheap ($270) but made a big difference to the handling and the front end no longer dived like a submarine every time I rolled off the gas
Yes, a piece of PVC pipe the right diameter is ideal for fitting new fork seals and also glad wrap over the top of the fork tube makes it easier and less damaging when sliding the new seal on. I put too lighter fork oil in for a start and it made my action too quick on the return stroke (not enough rebound damping) which buggered up my handling a bit. So dont use 5w fork oil!
Keep the blog entries coming

Good job on the forks, and write up! I bought a '94 GSXR400 a couple of years ago and while the forks were'nt rusted like yours they were in bad need of attention. The GSXR actually has USD's which is not common on those 250/400 fours form the late eighties onwards. Most of them have too softer springs from the factory so i put some stiffer racetech springs in there at the same time I had them apart. Not real cheap ($270) but made a big difference to the handling and the front end no longer dived like a submarine every time I rolled off the gas
Yes, a piece of PVC pipe the right diameter is ideal for fitting new fork seals and also glad wrap over the top of the fork tube makes it easier and less damaging when sliding the new seal on. I put too lighter fork oil in for a start and it made my action too quick on the return stroke (not enough rebound damping) which buggered up my handling a bit. So don't use 5w fork oil!
Keep the blog entries coming

Awesome feedback and much appreciated, its funny how each time you do a job you will find new and better ways of doing things. I fitted the seals and of course after fitting them realized about the glad wrap trick after stuffing around trying to be careful installing them. I have done this job on a different set of forks and did use that trick but its so long ago i didn't consider it at all when doing this install.

I cant remember what grade oil i used I must have a look and of course see how the handling is. I suspect it will be average and either an oil change will be needed or oil and springs. I didn't go down the spring route yet as I had so much expense everywhere else on this bike and really just wanted to get back to standard and see how I felt about it first before doing anything extra.

I have a GSXR750 so my go fast and handling issues are fairly sorted and the 400RR is really a nostalgic bike for me as i just have always liked those older bikes and had to have one. I need to add another RGV to the shed and a NSR but finding those at the right price is not easy these days. My friend had a GSXR400rr some years back and that was a fun machine also. I loved the upside down forks on them and like the RGV they were the only bikes with that tech at that time.

I will be doing another write-up soon but I was waiting on parts and that had been holding me up. I am not happy either with the front clock stay as i found better ways of cleaning it all up after i had completed that bit so i will revisit it and removed all the rust totally and replace all the rust bolts etc. I am about a week away from having another write-up ready. I am in the process also of filming all the new updates as its a lot faster for me to update the project that way.

Andy0501
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10th January 2018 00:45

Originally Posted by Southern scratcher

Good job on the forks, and write up! I bought a '94 GSXR400 a couple of years ago and while the forks were'nt rusted like yours they were in bad need of attention. The GSXR actually has USD's which is not common on those 250/400 fours form the late eighties onwards. Most of them have too softer springs from the factory so i put some stiffer racetech springs in there at the same time I had them apart. Not real cheap ($270) but made a big difference to the handling and the front end no longer dived like a submarine every time I rolled off the gas
Yes, a piece of PVC pipe the right diameter is ideal for fitting new fork seals and also glad wrap over the top of the fork tube makes it easier and less damaging when sliding the new seal on. I put too lighter fork oil in for a start and it made my action too quick on the return stroke (not enough rebound damping) which buggered up my handling a bit. So dont use 5w fork oil!
Keep the blog entries coming

Awesome work... truly inspiring. Did you do it by yourself or someone else helped you up?

Awesome work... truly inspiring. Did you do it by yourself or someone else helped you up?

YouTube helped a lot along with a dodgy copy of the service manual. I have been working on it by myself but its a slow process as the funds have been limited and as you know everything costs a small fortune and lots of time.

I didnt get to do much of anything recently as i was busy waiting for parts but will do another write-up soon to explain the latest updates.